1. Technical Field
The present invention relates to an inflator for an inflatable vehicle occupant restraint, such as an air bag, and in particular relates to a prefilter for an inflator having gas generating material which ignites to generate gas to inflate the inflatable vehicle occupant restraint.
2. Description of the Prior Art
An inflatable air bag which is inflated to protect an occupant in a vehicle when the vehicle encounters a situation which requires inflation of the air bag, such as a collision, is known. The air bag is in fluid communication with an actuatable inflator that provides inflation fluid for inflating the air bag.
One type of inflator includes ignitable gas generating material. The inflator is actuated by igniting the gas generating material. A common gas generating material includes a metal azide. Ignition of the gas generating material produces combustion products including hot nitrogen gas and hot particles. The nitrogen gas flows from the inflator to inflate the air bag. The flow of the nitrogen gas carries at least some of the hot particles with it.
A prefilter is typically located in the inflator and surrounds the gas generating material. Other filters in the inflator are located downstream of the prefilter. The prefilter is generally formed from a wire mesh. The prefilter cools the hot nitrogen gas and removes some of the hot particles from the flow of nitrogen gas.